1. Field of the Invention
The present invention relates to a heating body.
2. Description of the Related Art
Generally, a heating body includes a filament that is a heating part, a quartz tube into which the filament is inserted, and a connection part for connecting the filament to an external power source. The heating body converts an electric energy into a thermal energy to emit heat.
In detail, a filament formed of carbon is disposed at a center portion of the quartz tube, and the filament is connected to an external power source by the connection part, or the like. An inside of the quartz tube is vacuum or is filled with an inert gas such as a halogen gas. Therefore, when the carbon filament emits heat at a high temperature, an oxidation thereof is suppressed, which extends life of the heating body.
The carbon filament has a shape such as a spiral shape, a plate shape, a linear shape, or the like. A clip is used or a spring is employed for maintaining a tension in order to connect the carbon filament to an electrode. Using the above-mentioned methods, the carbon filament is disposed inside the quartz tube without contacting the quartz tube. The quartz tube melts or is damaged at more than approximately 800° C. Accordingly, when the carbon filament that is emitting heat contacts the quartz tube, the quartz tube is damaged, so that life of the heating body reduces. Therefore, as described above, the carbon filament is prevented from contacting the quartz tube using the clip or the spring.
However, in a related art heating body, the carbon filament is extended by external force and thus prevented from contacting the quartz tube. In such a structure, the carbon filament expands according to its thermal expansion coefficient when emitting heat at a high temperature. Therefore, the carbon filament further extends and eventually physically contacts the quartz tube, so that the quartz tube is damaged, which leads to reduction of life of the heating body.